The present invention relates to laminated glassware and is primarily concerned with the manufacture of strong, lightweight glass articles comprising color decorations which are useful for tableware, for lighting, and for other applications utilizing decorated glass.
U.S. Pat. No. 3,673,049 to Giffen et al. discloses a laminated glass body comprising a tensilely stressed core portion and an adherent, compressively stressed surface layer substantially enveloping the core portion, made by a continuous hot-forming process. Such laminates are useful for the production of strong, lightweight dinnerware and the like, the compressive stresses therein rendering the laminates highly resistant to mechanical breakage.
The decoration of laminates such as described in the aforementioned Giffen et al. patent is presently accomplished by means conventional for dinnerware, e.g., through the use of ceramic decals or similar decorating media which permit the application of color designs to the outer surfaces of the laminates. Such conventional decorations are subject to mechanical and chemical attack in use; thus special glazing compositions and high temperature firing treatments are utilized to insure adequate service life.
Although integrally colored glasses have been used to provide decorative glass and ceramic ware of high durability, the use of colored glass is not a very flexible design technique, particularly where large quantities of ware having different designs are to be produced. For this purpose, design methods permitting the application of any one of a large number of different designs to a single product or a small number of related products are preferred.
Very recently, photosensitive glasses which can be treated in the solid state to impart integral coloration over an extremely wide range of colors have been discovered. Hence U.S. Pat. No. 4,017,318 to Pierson and Stookey discloses photosensitive glasses containing silver, alkali metal oxides, fluorine, at least one of chlorine, bromine and iodine, and, optionally, CeO.sub.2, which glasses can be treated utilizing a sequence of high energy radiation and heating steps to produce integral coloration therein. Thus multi-colored photographs and other decorative designs can be developed in these glasses with a great deal of design flexibility.
The production of strong, lightweight glass articles from photosensitive glasses such as described in the aforementioned patent is difficult. The colors developed in such glasses are modified by exposure to high temperatures, such that air tempering and other strengthening methods involving heating have only limited utility. Similarly, the development of color in such glass requires treatment at elevated temperatures such that tempered or otherwise strengthened ware cannot subsequently be decorated without loss of strength.
It is the principal object of the present invention to provide a strong, lightweight glass article comprising photosensitive glass which can be decorated without reducing the mechanical strength thereof.
It is a further object of the invention to provide a strong, lightweight glass article comprising integrally colored photosensitive glass.
Other objects and advantages of the invention will become apparent from the following detailed description thereof.